This invention relates to gas turbine engines, and more particularly to mounting arrangements for variable stator vanes in gas turbine engines.
It is known to provide variable stator vanes (VSVs) in gas turbine engines, to improve their performance and stability, especially where high pressure ratios are required. Such vanes are able to pivot about a substantially radial axis, so as to change the angle they present to the incoming air. VSVs that are situated before the first rotor stage of a compressor are commonly referred to as variable inlet guide vanes (VIGVs).
VSVs have a spindle at each end; the spindles are located in bushes fitted into a pivot ring. For ease of assembly and disassembly, the pivot ring is usually made in two semicircular sections. Known pivot rings are commonly made from aluminium, and require complex machining during manufacture, both to form the functional shape of the ring and for weight reduction. Bushes, typically of Vespel, are fitted into holes in the ring and provide bearing surfaces for the VSVs. The fitting of the bushes adds further cost and complexity to the manufacture of the pivot ring.
It is an objective of this invention to provide a mounting arrangement for VSVs that overcomes the disadvantages of cost and complexity associated with known pivot rings.